Blood pump device and method of producing

ABSTRACT

The present invention pertains to a blood pump device which comprises a blood pump having blood transport ports and cannulae connected to the ports. The blood pump device also comprises a coating material covering the junction between the inner surfaces of the ports and cannulae. This forms a smooth transition so blood can flow unimpeded therefrom and collection cavities for the blood are eliminated. The invention is also related to a method of producing a smooth coating. The present invention is a blood pump device comprising a second portion having a stator mechanism and a rotor mechanism disposed adjacent to and driven by the stator mechanism. The second portion has a journal disposed about the rotor mechanism to provide support therewith. The second portion has an impeller disposed in the chamber and a one-piece seal member for sealing about a shaft of the impeller. The seal member is fixedly attached to the journal so that the seal member is supported by the journal. The present invention is also related to means for providing power to the blood pump so that blood can be pumped through a cannulae. The providing means includes a controller having means for sensing pump failure and an output terminal for actuating a safety occluder in an event of pump failure. Preferably, there is a safety occluder device disposed about the cannulae and in communication with the output terminal. Preferably, the blood pump comprises a motor having stator mechanism and a rotor mechanism driven by the stator mechanism. The sensing means comprises means for determining back electromagnetic force within the stator mechanism. Preferably, the controlling means has means for providing signals indicate of stator current and rotor speed, respectively. The providing means is in communication with the means for determining back electromagnetic force in the stator mechanism.

FIELD OF THE INVENTION

The present invention is related in general to medical devices. Morespecifically, the present invention is related to a blood pump devicefor cardiac assist.

BACKGROUND OF THE INVENTION

Ventricular assist devices are receiving ever-increasing attention inour society where 400,000 Americans are diagnosed with congestive heartfailure each year (Rutan, P. M., Galvin, E. A.: Adult and pediatricventricular heart failure, in Quall, S. H. (ed), Cardiac MechanicalAssistance Beyond Balloon Pumping, St. Louis, Mosby, 1993, pp. 3-24). Asa result, collaborative efforts among health care professionals havefocussed on the development of various systems to assist the failingheart. These comprise both extracorporeal and implantable pulsatileventricular assist devices (VAD), as well as non-pulsatile assist pumps.

Extracorporeal systems include the Pierce-Donachy VAD and the AbiomedBVS-5000 VAD. The Pierce-Donachy VAD is positioned on the patient'sabdomen and propels blood by means of a pneumatically actuateddiaphragm. Its use as a bridge to transplant is well-documented (Pae, W.E., Rosenberg, G., Donachy, J. H., et al.: Mechanical circulatoryassistance for postoperative cardiogenic shock: A three-year experience.ASAIO Trans 26:256-260, 1980; Pennington, D. G., Kanter, K. R., McBride,L. R., et al.: Seven years' experience with the Pierce-Donachyventricular assist device. J Thorac Cardiovasc Surg 96:901-911, 1988).The Abiomed BVS-5000, also an extracorporeal device, is fixed verticallyat the patient's bedside and is attached to the heart with percutaneouscannulae that exit the patient's chest below the costal margin(Champsaur, G., Ninet, J., Vigneron, M., et al.: Use of the Abiomed BVSSystem 5000 as a bridge to cardiac transplantation. J Thorac CardiovascSurg 100:122-128, 1990).

The most frequently used implantable systems for clinical applicationinclude the Novacor VAD (Novacor Division, Baxter Health Care Corp.) andthe Heartmate (Thermocardiosystems) (Rowles, J. R., Mortimer, B. J.,Olsen, D. B.: Ventricular Assist and Total Artificial Heart Devices forClinical Use in 1993. ASAIO J 39:840-855, 1993). The Novacor uses asolenoid-driven spring to actuate a dual pusher plate. The pusher platecompresses a polyurethane-lined chamber which causes ejection of blood(Portner, P. M., Jassawalla, J. S., Chen, H., et al: A new dualpusher-plate left heart assist blood pump. Artif Organs (Suppl)3:361-365, 1979). Likewise, the Heartmate consists of a polyurethanelined chamber surrounded by a pusher plate assembly, but a pneumaticsystem is used to actuate the pusher plate (Dasse, K. A., Chipman, S.D., Sherman, C. N., et al.: Clinical experience with textured bloodcontacting surfaces in ventricular assist devices. ASAIO Trans33:418-425, 1987).

Efficacy of both the extracorporeal and implantable pulsatile systemshas been shown (Rowles, J. R., Mortimer, B. J., Olsen, D. B.:Ventricular Assist and Total Artificial Heart Devices for Clinical Usein 1993. ASAIO J 39:840-855, 1993). However, certain complications areassociated with the use of extracorporeal systems, including relativelylengthy surgical implantation procedures and limited patient mobility.The use of totally implantable systems raises concerns such as high costof the device, complex device design, and again, relatively difficultinsertion techniques.

Centrifugal pump VADs offer several advantages over their pulsatilecounterparts. They are much less costly; they rely on less complicatedoperating principles; and, in general, they require less involvedsurgical implantation procedures since, in some applications,cardiopulmonary bypass (CPB) is not required. Thus, an implantablecentrifugal pump may be a better alternative to currently availableextracorporeal VADs for short- or medium-term assist (1-6 months). Inaddition, the use of centrifugal pumps in medium-term applications (1-6months) may allow the more complex, expensive VADs, namely the Novacorand the Heartmate, to be used in longer term applications where highercost, increased device complexity, and involved surgical procedures maybe justified.

Prior art relating to centrifugal blood pumps is Canadian Patent No.1078255 to Reich; U.S. Pat. No. 4,927,407 to Dorman; U.S. Pat. No.3,608,088 to Dorman; U.S. Pat. No. 4,135,253 to Reich; Development ofthe Baylor-Nikkiso centrifugal pump with a purging system forcirculatory support, Naifo, K., Miyazoe, Y., Aizawa, T., Mizuguchi, K.,Tasai, K., Ohara, Y., Orime, Y., Glueck, J., Takatani, S., Noon, G. P.,and Nose', Y., Artif. Organs, 1993; 17:614-618; A compact centrifugalpump for cardiopulmonary bypass, Sasaki, T., Jikuya, T., Aizawa, T.,Shiono, M., Sakuma, I., Takatani, S., Glueck, J., Noon, G. P., Nose',Y., and Debakey, M. E., Artif. Organs 1992;16:592-598; Development of aCompact Centrifugal Pump with Purging System for Circulatory Support;Four Month Survival with an Implanted Centrifugal Ventricular AssistDevice, A. H. Goldstein, MD; U.S. patent application titled “RadialDrive for Implantable Centrifugal Cardiac Assist Pump”, University ofMinnesota; Baylor Multipurpose Circulatory Support System forShort-to-Long Term Use, Shiono et al., ASAIO Journal 1992, M301.

Currently, centrifugal pumps are not implantable and are used clinicallyonly for CPB. Examples include the Biomedicus and the Sarns centrifugalpumps. The Biomedicus pump consists of an impeller comprised of stackedparallel cones. A constrained vortex is created upon rotation of theimpeller with an output blood flow proportional to pump rotational speed(Lynch, M. F., Paterson, D., Baxter, V.: Centrifugal blood pumping foropen-heart surgery. Minn Med 61:536, 1978). The Sarns pump consists of avaned impeller. Rotation of the impeller causes flow to be drawn throughthe inlet port of the pump and discharged via the pump outlet port(Joyce, L. D., Kiser, J. C., Eales, F., et al.: Experience with theSarns centrifugal pump as a ventricular assist device. ASAIO Trans36:M619-M623, 1990). Because of the interface between the spinningimpeller shaft and the blood seal, several problems exist with boththese pumps, including excessive wear at this interface, thrombusformation, and blood seepage into the motor causing eventual pumpfailure (Sharp, M. K.: An orbiting scroll blood pump without valves orrotating seals. ASAIO J 40:41-48, 1994; Ohara, Y., Makihiko, K., Orime,Y., et al.: An ultimate, compact, seal-less centrifugal ventricularassist device: baylor C-Gyro pump. Artif Organs 18:17-24, 1994).

The AB-180 is another type of centrifugal blood pump that is designed toassist blood circulation in patients who suffer heart failure. Asillustrated in FIG. 1, the pump consists of seven primary components: alower housing 1, a stator 2, a rotor 3, a journal 4, a seal 5, animpeller 6, and an upper housing 7. The components are manufactured byvarious vendors. The fabrication is performed at Allegheny-SingerResearch Institute in Pittsburgh, Pa.

The rotor 3 is in the lower housing 1 and its post protrudes through ahole in the journal 4. The impeller 6 pumps blood in the upper housing 7and is threaded into and rotates with the rotor 3. The impeller shaftpasses through a rubber seal 5 disposed between the upper housing 7 andthe journal 4, rotor and stator assembly. The upper housing 7 isthreaded into the lower housing 1 and it compresses the outer edge of arubber seal 5 to create a blood contacting chamber. In this manner,blood does not contact the rotor 3, journal 4, or lower housing 1. Theupper housing 7 is connected to an inlet and outlet flow tubes 8, 9,called cannulae, that are connected to the patient's circulatory system,such as between the left atrium, LA, and the descending. thoracic aorta,DTA, respectively. Through this connection, blood can be drawn from theleft atrium, LA, through the pump, and out to the aorta, DTA.

The impeller 6 spins by means of the rotor 3 and stator 2 which make upa DC brushless motor. The base of the rotor 3 has four magnets that makeup two north-south pole pairs which are positioned 90 degrees apart. Thestator 2 is positioned around the rotor 3 on the lower housing 1. Thestator 2 comprises three phases. When it is energized, it creates amagnetic force that counteracts the magnets in the rotor 3 causing therotor 3 and impeller 6 to spin, as is well known with brushless DCmotors.

A peristaltic pump infuses lubricating fluid into a port of the lowerhousing to lubricate the spinning rotor. The fluid prevents contactbetween any solid internal pump components during pump activation. Itforms a layer of approximately 0.001 inches around the rotor and theimpeller shaft. This fluid bearing essentially allows wear-freeoperation of the pump. The fluid passes around the rotor and flows upalong the rotor post. Eventually, it passes out through the rubber seal5 and into the upper housing 7 at the impeller shaft/seal interface.Fluid does not escape through the outer periphery of the housing sealbecause the upper housing is tightened down and sealed with a rubberO-ring to prevent leakage.

The spinning impeller 6 within the top housing 7 causes fluid to bedrawn from the inlet flow tube 8 toward the eye of the impeller. Theimpeller 6 then thrusts the fluid out to the periphery of the upperhousing 7. At this point, the fluid is pushed through the outlet tube 9by centrifugal force. The pump typically consumes 3-5 Watts of inputpower to perform the hydraulic work necessary to attain significantphysiologic benefits.

The prior art AB-180 pump has certain drawbacks which limit its efficacyas a cardiac assist device. The present invention describes severaldiscoveries and novel constructions and methods which vastly improvesuch a pump's operation.

SUMMARY OF THE INVENTION

The present invention pertains to a blood pump device. The blood pumpdevice comprises a blood pump having blood transport ports and cannulaeconnected to the ports. The blood pump device also comprises a coatingmaterial covering the junction between the inner surfaces of the portsand cannulae. This forms a smooth transition so blood can flow unimpededtherefrom and collection cavities for the blood are eliminated. Theinvention is also related to a method of producing a smooth coating.

The present invention is a blood pump device comprising a second portionhaving a stator mechanism and a rotor mechanism disposed adjacent to anddriven by the stator mechanism. The second portion has a journaldisposed about the rotor mechanism to provide support therewith. Thesecond portion has an impeller disposed in the chamber and a one-pieceseal member for sealing about a shaft of the impeller. The seal memberis fixedly attached to the journal so that the seal member is supportedby the journal.

Preferably, the rotor has a rotor post connected to the impeller shaftand an end adjacent to the seal member. The end has rounded edges toprevent abutment against any adhesive material disposed between the sealmember and the journal.

The present invention is also a blood pump device which has an infusionport for providing lubricant material about the rotor, the infusion porthas an inner diameter greater than 0.05 inches for minimizing pressureneeded to introduce lubricant material into the blood pump.

The present invention is also related to means for providing power tothe blood pump so that blood can be pumped through a cannulae. Theproviding means includes a controller having means for sensing pumpfailure and an output terminal for actuating a safety occluder in anevent of pump failure. Preferably, there is a safety occluder devicedisposed about the cannulae and in communication with the outputterminal. Preferably, the blood pump comprises a motor having statormechanism and a rotor mechanism driven by the stator mechanism. Thesensing means comprises means for determining back electromagnetic forcewithin the stator mechanism. Preferably, the controlling means has meansfor providing signals indicate of stator current and rotor speed,respectively. The providing means is in communication with the means fordetermining back electromagnetic force in the stator mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, the preferred embodiment of the inventionand preferred methods of practicing the invention are illustrated inwhich:

FIG. 1 is a schematic representation showing a centrifugal blood pumpdevice of the prior art.

FIG. 2 is a schematic representation showing the blood pump device ofthe present invention and an associated system.

FIGS. 3 a and 3 b are schematic representations showing a bloodcollection cavity at the junction between port and cannulae and coatingmaterial over the junction between port and cannulae, respectively.

FIGS. 4 a and 4 b are schematic representations showing a prior art sealconstruction and the present inventions seal construction, respectively.

FIGS. 5 a and 5 b are schematic representations showing a prior artrotor post and the rotor post of the present invention, respectively.

FIGS. 6 a and 6 b are schematic representations showing a prior artinfusion port and the infusion port of the present invention,respectively.

FIGS. 7 a and 7 b are schematic representations showing a mold forcasting the stator of thermally conductive epoxy.

FIG. 8 is a schematic representation showing the housing jig of thecannulae coating apparatus.

FIG. 9 is a schematic representation showing the cannulae coatingapparatus.

FIG. 10 a is a photograph showing a massive clot on the impeller and atshaft/seal interface from the 14-day study.

FIG. 10 b is a photograph showing a clot-free pump seal in the 10-daystudy.

FIG. 10 c is a photograph showing a 2 mm clot at the shaft/sealinterface in the 28-day study.

FIG. 10 d is a photograph showing a clot-free pump seal in the 154-daystudy.

FIGS. 11 a and 11 b are photographs showing rust on the rotor in the14-day study and no rust present in the 154-day study, respectively.

FIGS. 12 a and 12 b are photographs showing the prior art stator and thestator of the present invention, respectively.

FIG. 13 is a block diagram of one embodiment of the sensorless bloodpump controller in accordance with the present invention showing theexternal connections to the personal computer BLDC motor (blood pumpdevice), occluder, extended battery supply, power supply, and infusionpressure input.

FIG. 14 is a block diagram of one embodiment of the sensorless bloodpump controller in accordance with the present invention showing thecomponents that control and regulate and monitor the operation of thesensorless blood pump controller.

FIG. 15 is a block diagram of one embodiment of the sensorless bloodpump controller in accordance with the present invention showing theinternal power supply, external power supply, battery back-up, andbattery charger circuits.

FIG. 16 is a block diagram of one embodiment of the sensorless bloodpump controller in accordance with the present invention showing thepower distribution.

FIG. 17 is a block diagram of one embodiment of the sensorless bloodpump controller in accordance with the present invention showing theControl Entry Device as used with the control entry microcomputer andthe control computer.

FIG. 18 is a flowchart showing the start-up sequence for the motor, themeasurement of the pump parameters, display of pump parameters, anddownloading of pump parameters to an IBM personal computer.

FIG. 19 is a block diagram of one embodiment of the sensorless bloodpump controller in accordance with the present invention showing thesignal conditioner inputs to the control microcomputer, the output thatcompensates for a retrograde flow, the alarm that is activated for lowinfusion pressure, the low battery indicator, the occluder output, thealphanumeric LCD display, and the connection to an external IBMcomputer.

FIG. 20 is a flowchart of the error checks including blood pumpmalfunction, retrograde flow and low infusion pressure that results in acorrective action or alarm.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings wherein like reference numerals refer tosimilar or identical parts throughout the several views, and morespecifically to FIG. 2 thereof, there is shown a blood pump device 10.The blood pump 10 comprises a blood pump 12 having a blood transportport 14 and a cannulae 16 connected to the port 14. As best shown inFIG. 3 b, the blood pump device 10 also comprises a coating material 18covering the junction between the inner surfaces of the port 14 andcannulae 16 so that a smooth transition surface 20 is formed and bloodcan flow smoothly therefrom and collection cavities for the blood areeliminated.

The inlet cannulae 16 can be inserted into the left atrium of thepatient 22 and fixed with a double purse string suture. The outletcannulae 15 can be sewn to the aorta of the patient 22. The innerjunctions of the cannulae 15, 16 are coated with a polyurethane coatingmaterial 18 such as Biomer, manufactured by Ethicon, Inc. The coatingmaterial 18 provides a smooth transition surface 20 for the blood toflow on. This uniform transition is essential for reduction of clotformation.

The technique used to apply this coating material 18 is novel. Itinvolves applying the polyurethane material 18 to the collection cavity93 at the cannulae/port internal interface with a needle and syringe.After the polyurethane 18 is deposited, it is distributed evenly by handrotation of the housing.

Next, as shown in FIGS. 9 and 10, the upper housing 26 is spun axiallyfor each cannula 15, 16 in a motor driven coating chamber 92 for 24hours. This promotes more uniform distribution of the polyurethane 18and allows full curing. It also assures that the polyurethane coating 18fills the step-off between the housing ports and the cannulae. Thecoating chamber 92 consists of a motor shaft 94 enclosed by a plexiglassbox 96. The shaft 94 is connected to a variable speed motor 95protruding through the rear of the box. Nitrogen is passed through a jig97 which fastens to the motor 95 and holds the pump housing 26 andcannulae 15, 16. The jig 97 directs nitrogen from container 98 to passover the junction being coated. The nitrogen carries away the solventgases from the polyurethane 18 that would otherwise attack and degradeother areas of the pump housing 26. The custom jig 97 functions to holdthe top housing 26 in both configurations, one for coating the inletflow cannulae 15 and the other for coating the outlet flow cannulae 17.Once the polyurethane 18 is cured and evenly distributed, the housing 26is removed and the process is repeated for the other cannula.

As shown in FIG. 3 a, a prior art pump without the coating techniqueforms a collection cavity 93. The prior art blood pump was implanted in14 sheep in an experiment from December 1988 to October 1990. (ModifiedFabrication Techniques Lead to Improved Centrifugal Blood PumpPerformance, John J. Pacella et al., presented at the 40th AnniversaryMeeting of the American Society for Artificial Internal Organs, SanFrancisco, Calif., April 1994, incorporated by reference herein). Thepump was arranged extracorporeally in a left atrial to descending aorticcannulation scheme and the animals survived up to 13 days with theimplanted prior art device. These experiments revealed that a majorproblem of the prior art pump was thrombus formation within thecollection cavity 93 at the cannulae/housing interfaces.

In contrast, using the described antithrombogenic coating technique withcoating material 18, 44 sheep were implanted with the blood pump devicefrom 1992-1993 for periods of 1 day to 154 days and no thrombus wasfound at the interface. This represents a 100% success rate to date.

As shown in FIG. 2, the blood pump device 10 comprises a first portion28 having a chamber 30 and an inlet and outlet port 13, 14 in fluidiccommunication with the chamber 30. The blood pump device 10 alsocomprises a second portion 32 having a stator mechanism 34 and a rotormechanism 36 disposed adjacent to and driven by the stator mechanism 34.Together, the stator mechanism 34 and the rotor mechanism 36 form themotor 888. Preferably, the motor 888 is a brushless DC motor (BLDC) 888.The second portion 32 has a journal 38 disposed about the rotormechanism 36 to provide support therewith. The second portion 32 alsohas an impeller 40 disposed in the chamber 30 and a one-piece sealmember 42 for sealing about a shaft of the impeller 40. The seal member42 is fixedly attached to the journal 38, such as with adhesive, so thatthe seal member 42 is supported by the journal 38. Preferably, the sealmember 42 comprises a coating surrounding and sealing its outer surface.Further, the rotor 36 preferably has a surface 44 which has beenpolished to a surface finish of less than 2.54 μm for enhanced lowfriction operation. The amount of material removed from the rotor 36during the polishing process is less than 0.0001 inches (2.54 um).

As shown in FIGS. 4 a and 4 b, the hard plastic journal 38 and sealmember 42 is fastened together, such as with Loctite 401 adhesive, toachieve seal stiffness, which was previously provided by the metalinsert 45 molded into the prior seal 43. Also, the seal member 42 can becoated with Biomer (Ethicon, Inc.) polyurethane for enhancedantithrombogenicity.

Two improvements in pump characteristics have been made through this newseal 42. First, the cost of production of the seal member 42 has beendecreased significantly. The prior seal 43 had a metal insert 45 thatwas required to maintain seal stiffness, since the seal 43 is made ofsoft, flexible rubber. The disclosed construction of the presentinvention eliminates the need for an insert and simplifies the moldingprocess. The seal member 42 is glued directly to the journal 38, whichis made of hard plastic, to achieve overall seal stiffness. The processof gluing these two components is simple and relies on an inexpensiveadhesive. Second, this insert 45 had to be machined separately placed inthe rubber seal 43. As a result, the fabrication process of the sealleft metallic sections of the insert 45 exposed to fluid contaminationand therefore prone to rust. Since the seal member 42 of the presentinvention eliminates the insert, no steel is present for potential ironoxidation.

Further, the overall height, E, of the journal/seal assembly has beenincreased from approximately 0.928 inches to 0.944 inches. This hasresulted in a tighter seal at the junction between the outer rim 49 ofthe seal member 42 and the top housing 26, decreasing the chance forblood stasis and clot formation. As the top housing 26 is tightened downupon the lower housing 24 through their threaded connection, itcompresses the outer rim 49 of the seal 42. The increased journal/sealheight allows this compression to occur closer to the beginning of thethreads. In other words, the upper housing does not need to be rotatedas far through the threads to achieve the same tightness as it would ifthe journal/seal height, E, was not increased. Because of this, there ismore room to achieve a tighter seal.

The following are preferred dimensions of the seal constructions shownin FIGS. 4 a and 4 b:

-   -   A=0.273 in.    -   B=0.208 in.    -   C=0.06 in.    -   D=0.192 in.    -   E=0.944 in.

The journal/seal design, as shown in FIG. 4 b, has been used in thedisclosed sheep implantation studies and has functioned superbly.Results of the studies have shown inconsequential quantities of thrombusaround the periphery of the top housing 26 in a few cases and none inthe majority of the studies.

As best shown in FIG. 5 b, the top edge 50 of the rotor post 46 ispreferably rounded to allow a better fit under the seal member 42. Therotor post 46 is inserted into the journal 38 and fits just beneath theseal member 42. The junction between the journal 38 and the seal member46 occurs at this point and the two components are affixed with adhesive(i.e. Loctite 401). The rounding of the edge 50 on the rotor post 46prevents the rotor 36 from rubbing against any excess glue that may bepresent after the seal member 42 and journal 38 are fastened together.

The surfaces of the rotor 36 are preferably polished to 2.54 μm andgiven a rust-proof coating 58. Results from the sheep studies haverevealed little evidence of rust and polished surfaces have been shownto greatly increase durability between the rotor 36 and journal 38 andbetween the rotor 56 and the lower housing 60.

As best shown in FIGS. 6 a and 6 b, the infusion port 62 is preferablyenlarged from 0.03 inches to 0.062 inches. The housing 24 and port 62can also be cryogenically deburred. Further, a ¼ 28 UNF male luer lock66 is used instead of the prior ¼ 28 UNF threaded hex barb 68 toeliminate the male-female junction 64 at this point.

The port 62 serves as a passageway for pump lubricant, such as water orsaline, which is delivered to the pump and exits through the rubber sealmember 42 into the blood stream. The port 62 is enlarged because itassists in attaining lower pump lubricant pressures, which diminishesthe stress on all lubricant system components. Also, a small port ismore likely to become occluded with debris (e.g. salt deposit fromlubricant saline solution) and cause increases in lubricant pressures.

The male-female junction 64 in the previous design (FIG. 6 a) waseliminated to decrease the chance of foreign debris in the chest cavityfrom infiltrating into the lubricant system. The use of a threaded barb66 helps to solve this problem because there is one less junction. Thethreaded end is screwed into the lower housing 60 and chemically sealedand the barbed end is inserted directly into the lubricant tubing 69creating a mechanical seal.

The deburring of the housing 60 results in increased durability andimproved pump performance and lower internal lubricant temperatures. Theinternal lubricant temperature was measured by inserting an Omega, Inc33 Gauge hypodermic needle thermocouple directly through the pump baffleseal, just below the lip of the seal where the lubricant passes out. Wefound that rough (undeburred) component surfaces of the prior pumpresulted in internal lubricant temperatures of 50° C. The lubricanttemperatures of a pump device 10 with polished, deburred components wasfound to be 42-43° C., which is significantly less. Since heat isthought to be a possible contributor to thrombus formation, this mayhave increased the antithrombogenicity of the pump as well as increasingits durability.

As shown in FIGS. 7 a and 7 b, a new mold 70 was designed for statorfabrication. New, thermally conductive epoxy material is used forfabricating the stator 34. The new mold 70 has two halves 72, 74, aremovable center stem 76 and handles 78 for quick releasing of thehalves 72, 74. Fastening bolts 80 hold the halves 72, 74 and center stem76 together. The mold 70 has significantly increased the quality of thestator 34 as indicated by the progressive increases in the survivaltimes of sheep in the disclosed blood pump implantation studies. Inchronological order, the five studies of durations greater than ten dayswere 14, 10, 28, 35, and 154 day durations. The new mold 70 was used inthe 35 and 154 day studies.

Thermally conductive epoxy material was used for stator fabrication tohelp carry heat away from the stator 34 and allow it to conduct readilyto the surrounding tissues. As a result, the present stator 34 withthermally conductive epoxy has surface temperatures rarely exceeding2.5° C. above ambient temperature versus 5-7 C. in the 14 and 10 daystudies. Referring to FIG. 2, environmentally sealed connectors 72replace older style connectors used for controller/stator electricalconnections. Further, the stator 34 can be dip coated in polyurethanebefore potting.

A commercially available environmentally sealed connector 72 (LEMO USA,Inc.) is preferably used to prevent the electrical connections fromfailing in the event of exposure to fluid. The prior art connector wasnot waterproof. To hermetically seal the stator 34, it can be dipped inpolyurethane several times during the fabrication process. FIGS. 12 aand 12 b show the prior art stator and the stator 34 of the present pumpdevice 10.

The control means 80 of the present invention preferably has an output82 for actuation of a safety occluder device 83 in the event of motorfailure. Also, there are standardized outputs for current 84, speed 86,and lubricant system pressure 88 (0-1 Volt). The controller 80 usesisolated circuitry to cut down on noise by stator commutation. Threemeters 90 of a display means 81, with both digital and bar graph outputshow the outputs.

The automated occluder initiation output 82 greatly enhances safety forin vivo use of the blood pump. In the event of motor failure, detectedby back the EMF sensor means 92, the controller 80 will activate thesafety occluder device 83 to prevent retrograde pump flow through thecannulae 16. If pump current becomes zero, the controller 80 willattempt to restart the pump five times and if it is unsuccessful, itwill send a signal to actuate the occluder device 83 through output 82.The increased reliability allows more time for intervention andtroubleshooting. The standardized analog outputs for current 84, speed86, and perfusion pressure 88 (0-1 volt) provides enhanced andcomprehensive data collection. The outputs 84, 86, 88 can be used fortrend recording on a strip chart recorder 94, as opposed to directmeasurements once a day. Furthermore, isolated circuitry and displaymeans 89 with three meters 90 with both digital and bar graph outputwith ±1% accuracy on all readings prevent noise caused by statorcommutation and provides reliable data collection.

The controller in more detail is shown in FIG. 13.

The sensorless blood pump controller 80 is preferably used to controlthe motor 888. It is called sensorless because no sensors are disposedin the pump 12 itself. Referring to FIG. 14, a block diagram is providedof the preferred embodiment of many possible embodiments of thesensorless blood pump controller 80.

A highly integrated control I.C. 170, such as ML4411 available fromMicrolinear, San Jose, Calif., is comprised of the VCO 130 connected toa Back-Emf sampler 230 and to a logic and control 140. The control I.C.170 also includes gate drivers 240 for connection to power driver 260,linear control 901 connected to power driver 260 and I limit 110 andintegrator 101 and R sense 270. The control I.C. 170 additionallyincludes power fail detect 160. The ML4411 I.C. 170 provides commutationfor the BLDC motor 888 utilizing a sensorless technology to determinethe proper phase angle for the phase locked loop. The function andoperation of the specific features and elements of the control I.C. 170itself is well known in the art. Motor commutation is detected by theBack-EMF sampler 230.

For closed loop control, loop filter 900, connected to VCO 130 andamplifier 290, charges on late commutation, discharges on earlycommutation and is buffered by a non-inverting amplifier 290, modelLM324 available from National Semiconductor, Santa Clara, Calif. Thebuffered output provides feedback to the integrator 101 that includes aninverting amplifier, model LM324. Preferably, non-inverting amplifier290 and integrator 101 with an inverting amplifier are disposed on onechip. The speed control 120 uses a 20K ohm dailpot, model 3600S-001-203available from BOURNS, Riverside, Calif. The speed control 120 inconjunction with summer 700 provides the set point for integrator 101.The output from the integrator 101 is used in conjunction with the inputfrom R Sense 270, 0.05 ohms, part number MP821-0.05, available fromCaddock Electronics, Riverside, Calif., to the linear control 901 tomodulate gate drivers 240. The power drivers 260 consists of sixN-channel field effect transistors, part number RFP70N03, available fromHarris Semiconductor, Melbourne, Fla. The power drivers 260, connectedto the gate drivers 240, drive the BLDC motor 888.

The integrator 101 receives the desired speed control from the speedcontrol 120 and also receives a feedback signal from the control I.C.170 through its Back-EMF sampler 23 which passes the speed of the rotor36 in the BLDC motor 888. The output signal from the integrator 101,which essentially is an error correction signal corresponding to thedifference between the speed control set point signal and the sensedvelocity of the rotor mechanism 36 of the BLDC motor 888, is provided tothe linear control 901. The linear control 901, with the errorcorrection voltage signal from the integrator 101 and the voltage signalfrom the R sense 270, which corresponds to the stator mechanism 34current, modulates the gate drivers 240 to ultimately control thecurrent to the stator mechanism 34 of the DC motor 888. The R sense 270is in series with the power drivers 260 to detect the current flowingthrough the power drivers 260 to the stator mechanism 34 windings of theBLDC motor 888.

Power fail detect 160, an open collector output from the ML4411 controlI.C. 170, is active when the +12VDC or the +5VDC from the power supply180 is under-voltage. The power fail detect 160, alerts themicrocomputer 880 that a fault condition exists.

Referring to FIG. 15, external power supply 144 provides 12 VDC for thesensorless controller 80. Switching the external power supply 144 on oroff is accomplished by the on/off control entry microcomputer 800. Alogic ‘1’ gates the external power supply 1 off and vice-versa. Batteryback-Up is accomplished by solid state relay 777, P.N. AQV210, availablefrom AROMAT, New Providence, N.J. When external power is lost, theinternal power supply 180, P.N V1-J01-CY, available from Vicor, Andover,Mass. is enabled. The internal power supply 180 which derives power fromthe battery 490 P.N. V1-J01-CY, available from Vicor, Andover, Mass. isenabled. The internal power supply 180 derives power from the battery490 P.N. 642-78002-003, available from GATES, Gainsville, Fla. Chargerelay 333, P.N. 81H5D312-12, available from Potter and Brumfield,Princeton, Ind. switches out the external battery charger 214 when thecontrol entry microcomputer 800 is ‘ON’. Schottky diode 134, P.N.MBR1545, available from International Rectifier, Segundo, Calif.,performs a logic ‘OR’ on the External Power 144 or Internal power supply180 to the 12V Buss 250.

Referring to FIG. 16, power is derived from the 12V Buss 250 and feedsDC to DC converter 410, P.N. NME1212S, available from InternationalPower Sources, Ashland, Mass. and provides +12, −12V for the Analogcircuitry. The DC/DC converter 820, P.N. 78SR105 available from PowerTrends, Batavia, Ill. provides +5 VDC power for the DVM's and thecontrol I.C. 170. The DC/DC converter 122, P.N. 11450, available fromToko America, Prospect, Ill. provides +5VDC to the microcomputer 880.

Referring to FIG. 17, depression of the “ON” switch, p/o of switchassembly of the control entry device 190, P.N. 15.502, available fromSolico/MEC, Hartford, Conn., discharges capacitor (RC) p/o externalreset circuit 660 initiating a reset signal to the Control Entrymicrocomputer 800, P.N. PIC16C54, available from Microchip, San Jose,Calif. The control entry computer 800 toggles an I/O line to signal theExternal Power Supply 144 to power up and to turn status indicator 222on. The START, RESET, and MUTE lines from 190 are connected to resistorpack 480 P.N. R-9103-10K, available from Panasonic, Secacus, N.J. Thecontrol entry microcomputer 800, sends control lines including START,RESET, and MUTE to the control microcomputer 880, P.N. PIC16C71,available from Microchip, San Jose, Calif. and to the Status Indicators222, P.N. 16.921-08, available from Solic/MEC, Hartford, Conn.Depressing the START on control entry device 190 causes the ControlEntry microcomputer 800, to assert the START signal to Controlmicrocomputer 880. The Control microcomputer 880 initiates the sequenceto start the motor 888. Refer to FIG. 18. Upon successful completion ofthe START routine, referring to FIG. 19, the control microcomputer 880,digitizes three analog inputs including current conditioner 460connected to the motor 888, Infusion Pressure conditioner 280 and theinternal battery voltage 490. The Control I.C. 170 is connected to theRPM conditioner 380. The control microcomputer 880 is connected to theRPM conditioner 380. Referring to FIG. 18, the control microcomputer 880measures the period of the RPM input and calculates the RPM. Referringto FIG. 19, the control microcomputer 880 updates the LCD Display 603,P.N. 97-20947-0, available from EPSON, Terrance, Calif. and downloadsthe data including RPM, current, infusion pressure, and battery voltageto the external connection connecting the SBPC to the IBM printer port604. The control microcomputer 880 is connected to the alarm 602, P.N.P9923, available from Panasonic, Secaucus, N.J. and is activated whenthe infusion pressure is low. See FIG. 20. Upon an error detected withthe retrograde flow, the control microprocessor 880 of FIG. 19, outputsramped voltage to the digital to analog converter 500, P.N. MAX531,available from Maxim, Sunnyvale, Calif. The D/A converter 500 isconnected to an analog summer 700. The speed control 120 is connected tothe analog summer 700, which is part of four amplifiers in a package.P.N. LM324, available from national semiconductor, Santa Clara, Calif.The summer 700 is connected to the integrator 101. The integrator 101 isconnected to the control I.C. 170.

Referring to FIG. 20, the control microcontroller 880, upon detecting anerror that RPM is less than 2000 or zero motor current tries to restartthe motor 888 five times. After five times, if the motor 888 does notstart, then the SBPC activates an external occluder. See U.S. patentapplication Ser. No. ______, titled “Occluder Device and Method ofMaking”, by John J. Pacella and Richard E. Clark, having attorney docketnumber AHS-3, incorporated by reference herein, filed contemporaneouslywith this application for a description of the occluder.

An implantable centrifugal blood pump for short and medium-term (1-6months), left ventricular assist is disclosed in “Modified FabricationTechniques Lead to Improved Centrifugal Blood Pump Performance”, John J.Pacella et al., presented at the 40th Anniversary Meeting of theAmerican Society for Artificial Internal Organs, San Francisco, Calif.,April 1994. Pump operation such as durability and resistance to clotformation was studied. The antithrombogenic character of the pump 10 issuperior to prior art pumps due to the coating 18 at the cannula-housinginterfaces and at the baffle seal. Also, the impeller blade material hasbeen changed from polysulfone to pyrolytic carbon. The electroniccomponents of the pump have been sealed for implantable use throughspecialized processes of dipping, potting, and ultraviolet-assistedsealing. The surfaces of the internal pump components have been treatedin order to minimize friction. These treatments include polishing, iondeposition, and cryogenic deburring. The pump device 10 has demonstratedefficacy in five chronic sheep implantation studies of 10, 14, 28, 35and 113+ day durations. Post-mortem findings of the 14-day experimentrevealed stable fibrin entangled around the impeller shaft and blades.Following pump modification with refined coating techniques and advancedimpeller materials, autopsy findings of the ten-day study showed noevidence of clot. Additionally, the results of the 28-day experimentshowed only a small (2.0 mm) ring of fibrin at the shaft-seal interface.In this study, however, the pump failed on day 28 due to erosion of thestator epoxy.

In the experiments of 35 and 113+ day durations, the stators werere-designed, and the results of both experiments have shown no evidenceof motor failure. Furthermore, the 35-day study revealed a small depositof fibrin 0.5 mm wide at the lip of the seal. Based on these studies, itcan be ascertained that these new pump constructions have significantlycontributed to the improvements in durability and resistance to clotformation. In this study, the pump device 10 was implanted in five sheepfor a minimum of 10 days. Prior to surgery, the sheep were fasted for 24hours, but were allowed unlimited access to water. The pump device 10was implanted through a left thoracotomy and arranged in a leftatrial-to-descending aortic cannulation scheme. Two percutaneous tubeswere required for pump operation: one was used to jacket the conductorsthat supply power to the stator 34 and the other provided a conduit forpump lubricant infusion. The animals were infused at a constant ratewith either 0.9% saline or sterile water as the pump lubricant. Dailymeasurements of pump speed, current, voltage, flow, animal bodytemperature, and stator surface temperature were obtained. The animalswere free to ambulate within a 4-foot by 6-foot pen and were tethered toa custom-made swivel tether device as disclosed in U.S. Pat. No.5,305,712. Weekly blood draws consisted of blood counts, electrolytes,coagulation profiles, hepatic and renal function, and hemolysis. Bloodcultures were obtained as needed. The autopsy included completehistopathologic studies and a microscopic analysis of the pump 10.

Various modifications in the pump configuration throughout the course ofthe five studies were made to improve the antithrombogenicity, corrosionresistance, and durability of the pump. Antithrombogenicity wasaddressed by applying polyurethane coatings to the cannulae housinginterface and the seal and substituting pyrolytic carbon for polysulfoneas the impeller blade material. In addition, alterations in thelubricant infusion rate and the anticoagulation scheme wereincorporated. The rotor surfaces 46 were conditioned through polishingand passivating procedures with the goal of increasing pump durability,and the lower housing rotor bearing surface was cryogenically deburredfor the same purpose. Finally, the pump stator 34 was dip-coated inpolyurethane and potted in a larger sized mold to provide more materialcoverage of the stator to increase the resistance of the pump to fluidcorrosion.

Pump modifications were made continuously throughout the five studies,depending on the results of each preceding study, as shown below inTable I: TABLE I Result Dependent Modifications Experiment Duration(Days) Modification 14 10 28 35 154 Lower Housing X X Conditioning RotorConditioning X X Re-designed Stator X X Seal Coating X X X XCannula/Housing X X X X X Coating Impeller P C C¹ C¹ C¹ MaterialPerfusion Flow 2 4 10 10 10 Rate (ml/hr) Anticoagulation N H, S A, H, C,S A, H, C, S A, H, C, S, UN = none;A = aspirin;H = heparin;C = coumadin;S = streptokinase;U = urokinase;P = polysulfone;C¹ = pyroltic carbon

The 14-day study incorporated a prior art rotor and lower housing, apolysulfone impeller, and a polyurethane coating applied to thecannulae/housing interfaces. The lubricant flow rate was 2 ml/hr and noanticoagulants were used. Autopsy findings revealed a massive clotentangled within the impeller blades and fixed to the impeller shaft atthe shaft/seal junction, as shown in FIG. 10 a. The cannulae/housinginterfaces were free to clot due to the sealing material 18. Rust waspresent on the rotor, as shown in FIG. 11 a.

The second study of 10 days duration included pump alterationsconsisting of a polyurethane coating (Biomer, Ethicon, Inc.) applied tothe seal 42, a pyrolytic carbon impeller 40, a 0.9% saline lubricantflow rate of 4 ml/hr, and the use of heparin in the saline lubricant.Streptokinase was administered every third day with the lubricant. Theexplanted pump was found completely devoid of thrombus, as shown in FIG.10 b.

In a third study of 28 days duration, the pump was arranged similarly tothe 10-day study. However, the lubricant flow rate was increased to 10ml/hr and 325 mg aspirin and 5-20 mg coumadin were given daily by mouthto broaden the anticoagulant regimen. A 2 mm ring thrombus was found atthe impeller shaft/seal interface, as shown in FIG. 10 c, and the motorwas found to be contaminated by chest cavity fluid as indicated bychemical corrosion of select stator windings.

The fourth study of 35 days used several of the new pump components.These comprised a stator 34 with several polyurethane coatings and anincreased epoxy potting thickness to prevent fluid corrosion, as shownin FIG. 12 b. Also, a thin layer of titanium ion-coating was used topassivate the rotor surfaces 46 and reduce the opportunity for rustformation. Furthermore, the lower housing bearing surface was deburredto decrease wear on the rotor 36. The perfusion flow rate andanticoagulation scheme remained unaltered in this study. The explantedpump had a small irregular ring clot of 0.5 mm at its widest pointsurrounding the impeller shaft/seal junction. The pump lubricant systembecame completely occluded due to precipitation of salt from the salinesolution. As a result, significant seepage of blood products below theseal caused increased friction between the rotor 36 and its bearingsurfaces and eventually caused pump stoppage. However, there were noemboli at autopsy.

The last study of 154 days duration included variations from theprevious study. For instance, thin layer chromium ion-coating was usedin place of titanium coating to passivate the rotor 36 because it wasavailable and cheaper. The lubricant was changed from 0.9% saline tosterile water on post-operative day (POD) 86 in order to reduce thechance of lubricant system occlusion due to salt precipitation. Next,based on published reports and preliminary studies of variousantithrombotic drugs in sheep, urokinase was used as an alternative tostreptokinase beginning on POD 130 because of its suspected superiorthrombolytic effect. This study revealed a pump devoid of thrombus andfree of measurable wear based on light microscopic and dimensionalanalysis, as shown in FIG. 10 d. Furthermore, no evidence of rust wasfound on the rotor surface, as shown in FIG. 11 b. However, the pumpstator 34 completely failed due to fluid corrosion.

The lubricant rate was increased from 2 to 10 ml/hr over the course ofthe five studies. The intention was to increase fluid washing of theseal/impeller shaft interface to prevent blood stasis and thrombusformation. Precipitated salt was identified as a potential source oflubricant blockage in the 35-day study. As a result, the 154-day studyunderwent a change in lubricant from 0.9% saline to sterile water. Thehematocrit and serum free hemoglobin measures were unaffected by thischange.

Efficiency was calculated for each study by applying interpolationtechniques to bench data of hydraulic performance and using pump inputpower as the product of pump voltage and current. Table II, shown below,shows stator temperature, animal body temperature, and their differencefor each experiment. The average difference between the stator surfacetemperature and the animal core temperature decreased from 5.5-7° C. inthe 14 and 10 day studies to approximately 1-3° C. in the 28, 35, and154-day studies: TABLE II Average Values of Pump Efficiency, StatorTemperature, Animal Temperature, and Temperature Difference for EachStudy Study Duration (days) 14 10 28 35 154 Pump Efficiency (%) 13.6 ±2.1 16.3 ± 4.7 20.5 ± 2.6 15.0 ± 1.6 13.2 ± 2.2 Stator Temperature (°C.) 45.4 ± 1.4 44.8 ± 1.4 41.8 ± 0.7 41.5 ± 0.7 41.6 ± 1.0 AnimalTemperature (° C.) 39.2 ± 0.3 39.0¹ 40.6 ± 0.7 39.0 ± 0.7 39.1 ± 0.6Temperature Difference² (° C.)  6.8 ± 1.5  5.8 ± 1.4  1.3 ± 0.7  2.4 ±0.5  2.6 ± 0.6Note:All values are averages over the course of each study¹Measurement taken on first post-operative day only.²Temperature Difference = Stator Temperature-Animal Temperature

The novel construction of the pump device 10 contributed to overallimproved pump performance as compared to previous pump devices.Conditioning of both the rotor 36 and lower housing surfaces hasincluded polishing and passivating and cryogenic deburring,respectively. These techniques provide even distribution of lubricantover the moving components, smoother surfaces for direct contact in theevent of lubricant system failure, and resistance to the oxidation ofiron. These studies show that passivation of the rotor surfaces causedelimination of rotor rust, as evidenced by a comparison of the prior artrotor used in the 14-day study (FIG. 11 a) with the chromium-coatedrotor used in the 154-day study (FIG. 11 b). The decreases intemperature difference between the stator and ambient can be related toincreases in lubricant flow rate from 2 to 10 ml/hr (Table II). Based onthese five studies, the implications are that the temperature differencebetween the stator surface and ambient decreased by means of increasedconvective heat loss through higher lubricant infusion rates.

Also, since this pump relies on a fluid bearing between the rotor andits adjacent surfaces, no correlation between efficiency and pumpsurface modification should necessarily be expected. That is, regardlessof the coefficient of static and dynamic friction between the rotor andjournal or rotor and lower housing, the no-slip condition for thelubricant holds at the solid surfaces, and the frictional losses areviscous in nature.

The polyurethane coatings have contributed significantly to theantithrombogenicity of the pump. Specifically, the application ofpolyurethane material 18 to the cannulae/housing interface has hadstriking results: no clots have been found in any of the five studies atthis juncture, nor have they been found in 39 other accumulatedimplantation studies. This has been a major improvement of the presentpump device 10 based on prior studies (Goldstein, A. H., Pacella, J. J.,Trumble, D. R., et al.: Development of an implantable centrifugal bloodpump. ASAIO Trans 38:M362-M365, 1992). In addition, the polyurethanecoating of the seal and the use of pyrolytic carbon impeller blades havebeen associated with decreased thrombus formation, as shown incomparisons of the first study of 14 days duration and all foursubsequent studies (10, 28, 35, and 154-day lengths).

The prevention of thoracic cavity fluid leakage into the electroniccomponents of the pump stator 34 through various environmental sealingtechniques has been of utmost importance. Developed methods involvecoating the stator windings in polyurethane and increasing the size ofthe stator mold to allow thicker epoxy coverage. As a result, theoccurrence of fluid-based corrosion has been significantly reduced. Noevidence of motor failure was found in the 35-day study; however, the154-day study was ended due to corrosion of the stator by chest fluid.In this study, the time to catastrophic motor failure secondary tocorrosion was increased significantly from the 28-day study.

The use of anticoagulation administered in all experiments following thefirst 14-day study appears to have contributed to a significantreduction in pump thrombosis. However, the role of specificanticoagulant drugs as antithrombotic agents in sheep will be addressedseparately.

The change from 0.9% saline lubricant to sterile water in the 154-daystudy on POD 86 was made based on the findings from the 35-dayexperiment. This change appears to have reduced the occurrence of saltdeposition within the occlusion system as indicated by decreasedvariation in the perfusion system pressures and flows and more reliabledelivery of lubricant to the pump.

Thus, with the present pump device, modifications in blood surfacematerials, blood surface coatings, and electronic component fabricationand environmental sealing have had a positive impact on pump performanceas indicated by increased survival times, decreased pump clot formation,less pump component wear, lower pump stator surface temperatures, andincreased in fluid corrosion resistance. Moreover, both the expense andthe learning curve associated with these long-term implantation studieshave prompted changes from one study to the next. For example, in the35-day study, salt thought to be was precipitating from saline solutiondue to low lubricant flow rates, blocking the lubricant conduit, andpreventing lubricant from reaching the pump. Eventually, pump failureoccurred. This knowledge was applied in an ongoing study of 154 days bysubstituting sterile water for saline. The result was increasedreliability of pump lubricant delivery and elimination of episodes offlow blockage.

The myriad of device-centered modifications in these studies were madewith the goals of achieving longer survival times, increasing pumpreliability, and proving feasibility of the device as a VAD. As aresult, the centrifugal pump has evolved through multiple intermediateforms, with increasing improvements in its performance.

Although the invention has been described in detail in the foregoingembodiments for the purpose of illustration, it is to be understood thatsuch detail is solely for that purpose and that variations can be madetherein by those skilled in the art without departing from the spiritand scope of the invention except as it may be described by thefollowing claims.

1. A blood pump device comprising: a blood pump having a blood transportport; a cannulae connected to the port; and a coating material coveringa junction between inner surfaces of the port and cannulae so that asmooth transition surface is formed so blood can flow smoothly therefromand collection areas for the blood are eliminated.
 2. A device asdescribed in claim 1 wherein the coating material is comprised ofpolyurethane.
 3. A method of producing a smooth transition junctioncoating between a blood pump and a cannulae comprising the steps of:connecting a cannulae to a port of a blood pump; and applying a coatingmaterial to cover a junction between inner surface of the port andcannulae so that a smooth transition surface is formed so blood can flowsmoothly therefrom and collection areas for the blood are eliminated. 4.A method as described in claim 3 wherein the applying step includes thesteps of injecting coating material through the cannulae about thejunction and rotating the port and cannulae to evenly distribute thecoating about the junction.
 5. A method as described in claim 4 whereinduring the rotating step, there is the step of circulating a fluidthrough the cannulae past the junction to carry away solvent gasesformed during curing of the coating material.
 6. A method as describedin claim 5 wherein the rotating step includes the step of spinning theport and cannulae with a motor device during curing of the coatingmaterial.
 7. A blood pump device comprising: a first portion having achamber and an inlet and outlet port in fluidic communication with thechamber; and a second portion having a stator mechanism and a rotormechanism disposed adjacent to and driven by the stator mechanism, saidsecond portion having a journal disposed about the rotor mechanism toprovide support therewith, said second portion having an impellerdisposed in the chamber and a one-piece seal member for sealing about ashaft of the impeller, said seal member fixedly attached to said journalso that the seal member is supported by the journal.
 8. A blood pump asdescribed in claim 7 wherein said rotor having a rotor post connected tothe impeller shaft and having an end adjacent to the seal member, saidend having rounded edges to prevent abutment against any adhesivematerial disposed between the seal member and the journal.
 9. A deviceas described in claim 8 wherein the journal has a surface adjacent tothe rotor which has been polished to a surface finish of less than 2.54μm for enhanced durability.
 10. A device as described in claim 9 whereinthe rotor has an outer surface which has been polished to a surfacefinish of 2.54 μm.
 11. A device as described in claim 10 wherein theseal member comprises a coating surrounding and sealing its outersurface.
 12. A device as described in claim 11 wherein the rotorcomprises a rust-proof coating disposed on its outer surface.
 13. Ablood pump device comprising: a first portion having a chamber and aninlet and outlet port in fluidic communication with the chamber; and asecond portion having a stator mechanism and a rotor mechanism disposedadjacent to and driven by the stator mechanism, said second portionhaving a journal disposed about the rotor mechanism to provide supporttherewith, said second portion having an impeller disposed in thechamber, said second portion having an infusion port for providinglubricant material about the rotor, said infusion port having an innerdiameter greater than 0.05 inches for minimizing pressure needed tointroduce lubricant material into the blood pump.
 14. A device asdescribed in claim 13 wherein said second portion having a barbed tubingconnector attached directly into a housing member of the second portionin direct fluid communication with the infusion port.
 15. A device asdescribed in claim 14 wherein the infusion port is polished to a surfacefinish of less than 2.54 μm.
 16. An improved blood pump devicecomprising: a first portion having a chamber and an inlet and outletport in fluidic communication with the chamber; and a second portionhaving a stator mechanism and a rotor mechanism disposed adjacent to anddriven by the stator mechanism, said second portion having a journaldisposed about the rotor mechanism to provide support therewith, saidsecond portion having an impeller disposed in the chamber, said statorcomprised of a thermally conductive epoxy material to efficientlytransmit heat to surrounding tissues about the blood pump.
 17. A deviceas described in claim 16 wherein the second portion comprises anenvironmentally sealed connector for attaching a power wire to thestator mechanism.
 18. A device as described in claim 17 wherein thestator has a coating sealing its outer surface.
 19. A blood pump devicecomprising: a blood pump; and means for providing power to the bloodpump so that blood can be pumped through a cannulae, said providingmeans comprising a controller having means for sensing pump failure andan output terminal for actuating a safety occluder in an event of pumpfailure.
 20. A device as described in claim 19 including a safetyoccluder device disposed about the cannulae and in communication withthe output terminal.
 21. A device as described in claim 20 wherein theblood pump comprises a motor having stator mechanism and a rotormechanism driven by the stator mechanism, said sensing means comprisesmeans for determining back electromagnetic force within the statormechanism.
 22. A device as described in claim 21 wherein saidcontrolling means having means for providing signals indicate of statorcurrent and rotor speed, respectively, said providing means incommunication with the means for determining back electromagnetic forcein the stator mechanism.
 23. A device as described in claim 22 includingmeans for supplying lubricant to the motor, said supplying means influidic communication with the blood pump, said controlling means havingmeans for measuring lubricant pressure.
 24. A device as described inclaim 23 wherein the power providing means comprises a modular driverunit remote from said pump and in communication therewith.
 25. A deviceas described in claim 24 wherein the controlling means comprises meansfor adjusting speed of the motor mechanism with a greater than 5%accuracy.
 26. A device as described in claim 25 wherein the controllingmeans comprises a display mechanism for providing values of statorcurrent, rotor speed and lubricant pressure.
 27. A pumping system forfluid comprising: a sensorless pump for moving the fluid; and acontroller connected to the pump for controlling the pump so a desiredflow rate of fluid can be maintained by the pump.